Reactive and Incompatible Chemicals ¹ This list includes only the most important examples. These chemicals react violently when they come into contact with each other and must not be stored together.Mixing incompatible chemicals in a waste container can form an explosive mixture, for example, nitric acid and ethanol. If a bottle broke in a waste storage area where incompatibles were present, the results could be disastrous. Remember: incompatible bottles of wastes should be stored separately. The objective is to avoid accidents in the laboratory. See table below for the possible reactions that may occur due to impropper storage of chemicals.

See also: immiscible solvents and solvent drying

Substance	Incompatible with
Acetic acid	Chromium oxide, nitric acid, perchloric acid, peroxides, permanganates, alcohol, ethylene glycol
Acetic anhydride	Hydroxyl-containing compounds e.g. ethylene glycol, perchloric acid
Acetone	Concentrated nitric acid and sulphuric acid mixtures, hydrogen peroxide
Acetylene	Chlorine, bromine, fluorine, copper, silver, mercury
Activated carbon	Calcium hypochlorite, oxidizing agents
Alkali metals	Water, carbon tetrachloride and other halogenated alkanes, carbon dioxide, halogens. (Do not use water or foam extinguishers for fires involving these metals Use the appropriate class D extinguisher.
Aluminium	All oxidizing agents, acids, alkalis, halogenated hydrocarbons, peroxides
Aluminium alkyls	water
Ammonia, liquid or gas	Mercury (e.g. in pressure gauges), chlorine, calcium hypochlorite, iodine, bromine, hydrogen fluoride
Ammonium nitrate	Acids, powdered metals, flammable liquids, chlorates, nitrates, sulfur, fine-particulate organic or combustible materials
Aniline	Nitric acid, hydrogen peroxide
Arsenic materials	Any reducing agent
Azides	Acids
Bromine	see chlorine
Calcium oxide	Water
Carbon activated	Calcium hypochlorite, other oxidants
Chlorine	Ammonia, acetylene, butadiene, butane, methane, propane, hydrogen, petroleum benzine, benzene, powdered metals
Chlorates	Ammonium salts, acids, powdered metals, sulfur, fine-particulate organic or combustible substances
Chromium (V1) oxide, chromic acid	Acetic acid, naphthalene, camphor, glycerol, petroleum benzine, alcohols, flammable liquids
Copper	Acetylene, hydrogen peroxide
Cumene hydroperoxide	Acids, both organic and inorganic
Cyanides	Acids
Flammable liquids	Ammonium nitrate, chromium (VI) oxide, hydrogen peroxide, nitric acid, sodium peroxide, halogens, chromic acid.
Fluorine	Extremely aggressive; store separately! Isolate from everything!
Hydrazine	Hydrogen peroxide, nitric acid, any other oxidant
Hydrocarbons butane, propane, benzene etc.	Fluorine, chlorine, bromine, chromium (VI) oxide, sodium peroxide
Hydrogen fluoride	Ammonia (laboratory gas or solutions)
Hydrogen peroxide	Copper, chromium, iron, metals and metal salts, alcohols, acetone, organic substances, aniline, nitromethane, combustible substances (solid or liquid)
Hydrogen sulphide	Fuming nitric acid, oxidizing gases
Hypochlorites	Acids, activated carbon
Iodine	Acetylene, ammonia (laboratory gas or solutions)
Mercury	Acetylene, ammonia
Nitrates and nitrites	Acids
Nitric acid	Acetic acid, aniline, chromium (VI) oxide, prussic acid, hydrogen sulfide, flammable liquids and gases
Nitroparaffins	Inorganic bases, amines
Oxalic acid	Silver, mercury, mercury salts
Perchloric acid	Acetic anhydride, bismuth and its alloys, alcohols, paper, wood, grease. oil, (all organics)
Peroxides, organic	Acids (organic and inorganic), avoid friction, store cold.
Phosphorus	Sulfur, compounds containing oxygen, e.g. chlorates, air, oxygen
Phosphorus pentoxide	Alcohols, strong bases, water
Potassium	Carbon tetrachloride,carbon dioxide, water
Potassium chlorate	see chlorate
Potassium perchlorate	see chlorate
Potassium permanganate	Glycerol, ethylene glycol, benzaldehyde, sulfuric acid
Silver	Acetylene, oxalic acid tartaric acid, ammonium compounds
Sodium	see alkali metals
Sodium peroxide	Methanol, ethanol, glacial acetic acid, acetic anhydride, benzaldehyde, carbon disulfide, glycerol, ethylene glycol, ethyl acetate, methyl acetate, furfural
Sulphides	Acids
Sulphuric acid	Potassium chlorate, potassium perchlorate, potassium permanganate
sulphur	Metals, all oxidizing agents
Zinc	All oxidizing agents, acids, alkalis, halogenated hydrocarbons, peroxides

Reactions of incompatible chemicals ²

Chemicals Stored Together	Possible Reaction
1. Acetic acid & Acetaldehyde	Small amounts of acetic acid will cause the acetaldehyde to polymerize, releasing heat.
2. Acetic anhydride & Acetaldehyde	Reaction can be violently explosive
3. Aluminum metal & ammonium nitrate	A potential explosive.
4. Aluminum & bromine vapor	Aluminum foil reacts with bromine vapor at room temperature and incandesces.
5. Ammonia vapor & bromine vapor	Unstable nitrogen tribromide is formed, explosion may result.
6. Ammonium nitrate & acetic acid	A mixture may result in ignition, especially if acetic acid is concentrated.
7. Cupric sulfide & cadmium chlorate	Will explode on contact.
8. Hydrogen peroxide & ferrous sulfide	Forms a vigorous, highly exothermic reaction.
9. Hydrogen peroxide & lead II or IV oxide	Violent, possibly explosive reaction.
10. Lead perchlorate & methyl alcohol	Forms an explosive mixture if agitated.
11. Lead sulfide & hydrogen peroxide	Vigorous, potentially explosive reaction.
12. Mercury II nitrate & methanol	May form mercury fulminate - an explosive.
13. Nitric acid & phosphorus	Phosphorus burns spontaneously in the presence of nitric acid.
14. Potassium cyanide & potassium peroxide	A potentially-explosive mixture if heated.
15. Sodium nitrate & sodium thiosulfate	A mixture of the dry materials can result in an explosion.

References :
1. Merck chemical company.
2. Chemical Safety Office, Risk Management Department, University of Vermont.
3. Hazards in the Chemical Laboratory, 4th. edition. 1986. Bretherick.